by Yousef Al-Helou, Ilana Conway and Jennifer Collins , Special for USA TODAY

by Yousef Al-Helou, Ilana Conway and Jennifer Collins , Special for USA TODAY

GAZA CITY - Israel bombed the Gaza Strip's only power plant Tuesday in a further sign that its military campaign against Hamas is showing few signs of slowing down as the conflict enters its fourth week.

In a separate development, a cease-fire proposed by a senior official from the Palestine Liberation Organization was later contradicted by Hamas.

Israeli tank shells hit a fuel tank - one of three - at the plant, forcing it to shut down, said Jamal Dardaswadi, a spokesman for the plant run by the Gaza Power Generating Company.

Even before the strike, Gaza residents said they were getting electricity for only about three hours a day. It was not immediately clear how the plant closure would affect power supply in Gaza.

Israeli aircraft, tanks and navy gunboats also targeted other symbols of Hamas control in Gaza on Tuesday, with strikes hitting the home of the top Hamas leader in Gaza, Ismail Haniyeh, as well as government offices and the headquarters of the Hamas satellite TV station.

Lt. Col. Peter Lerner, an Israeli military spokesman, did not comment on the explosion at the plant, but said that Israel's latest strikes signal "a gradual increase in the pressure" on Hamas.

Mohammed Deif, leader of the Hamas military wing, said his group will not cease fire until its demands are met. His rare remarks were broadcast late Tuesday on Al-Aqsa TV, the satellite station of Hamas.

"There is not going to be a cease-fire as long as the demands of our people are not fulfilled," he said.

Deif's voice was recognizable in the audio statement. He has survived repeated Israeli assassination attempts and has operated from hiding for years.

Earlier, a senior Palestinian official called for a 24-hour humanitarian cease-fire in Gaza, saying he was also speaking in the name of Hamas. Yasser Abed Rabbo, secretary general of the PLO, said Tuesday that Israel must bear the consequences if it rejects this call. However, a Hamas spokesman in Gaza, Sami Abu Zuhri, said that "the remarks of Mr. Abed Rabbo are not true and have nothing to do with the positions of the factions at the moment." Hamas is not a member of the PLO. Israel too brushed aside the offer, saying it needed to hear directly from Hamas.

Meanwhile, Hamas said it fired over a dozen rockets into Israel on Monday night.

Abu Abdallah, 43, a Hamas supporter in Gaza City, said he believes that Hamas is entitled to defend its territory against the Israeli strikes.

"Israelis keep saying that they have the right to defend themselves," said Abdallah. "What do you expect us to do when the enemy invades our territory?"

Earlier, Israeli Prime Minister Benjamin Netanyahu warned of a "prolonged" military campaign in Gaza as Israel has stepped up bombardments it says are aimed at preventing Hamas from firing rockets into Israel as well as demolishing the network of tunnels Palestinians use to bring goods and other materials into the area and to launch attacks on Israel.

Netanyahu said Monday that Israel won't end its offensive until Hamas' network of tunnels under the Gaza-Israel border has been neutralized.

"We need to be ready for a prolonged campaign," he said. "We will continue to act aggressively and responsibly until the mission is completed to protect our citizens, soldiers and children."

Hamas spokesman Sami Abu Zuhri responded defiantly. "His threats do not scare Hamas or the Palestinian people, and the occupation will pay the price for the massacres against civilians and children," he said.

At least 1,210 Palestinians have been killed, including 109 on Tuesday, since the fighting started July 8, Palestinian health official Ashraf al-Kidra said. He said 16 other people died of wounds sustained on previous days.

Israel has reported 53 soldiers and three civilians killed.

Palestinian leaders have vowed to fight on until their demands are met, in particular the lifting of a blockade on Gaza by Israel and Egypt.

In Israel, residents spoke of living with the threat of Hamas rocket fire for many years, and wanting to put a stop to it.

"Those living in south (Israel) have endured this every day for many, many years," said Shira Lang, who works in the hospitality and tourism industry in Tel Aviv, "(This) is something that people outside of Israel don't seem to realize," she said.

In another development, Ayatollah Ali Khamenei, Iran's supreme leader, called on Muslims around the world to "to arm the Palestinian nation by all means."